1. Field of the Invention
This invention pertains in general to high-speed data networks and in particular to a system and method for restricting access by servers on the network to resources available on user computer systems.
2. Background of the Invention
Cable television service is usually sold as a subscription to one or more “tiers” of channels. Typically, a basic cable subscription allows access to a small tier of channels and is sold for a relatively low subscription fee. The subscriber can purchase additional tiers of cable channels for additional fees.
In most cable systems, the subscriber uses a “set-top box” (STB) to access the cable channels. The STB contains a microprocessor and other hardware for tuning and descrambling channels in the tiers to which the subscriber has access. The STB may also enable other services, such as pay-per-view or digital music reception in return for additional fees.
In recent years, the STB has incorporated a cable modem that enables access to Internet- and World Wide Web- (“the web”) based resources via the cable infrastructure. A cable modem typically has at least one assigned Internet Protocol (IP) address and is managed by an Internet Service Provider (ISP). The ISP inserts and extracts Internet traffic to and from the cable infrastructure and distributes it to the cable modem having the given IP address or the Internet, as appropriate.
U.S. Pat. No. 6,678,733 discloses a walled garden accessible to STB users who are customers of the ISP. Application servers within the walled garden provide services to the users, including, for example, access to electronic content, access to electronic commerce services, and any other functionality that can be provided electronically via a network. The users can subscribe to one or more of the services in the walled garden either individually or as part of a tier. U.S. Pat. No. 6,678,733 discloses a way to restrict users to only those services in the walled garden to which the users are entitled to access.
The walled garden application servers may desire or need to access features of the users' STBs in order to provide certain services. For example, an application server may need to generate text or controls on a user's television display, change the channel to which the STB is tuned, print a receipt on a printer coupled to the STB, or complete a fee transaction using an electronic wallet stored in the STB.
The ISP would prefer to limit the features on the users' STBs to which the application servers have access, typically to generate revenue and enhance security. For example, the ISP may desire to charge a fee for letting an application server change the channel to which the user's STB is tuned or conduct an electronic commerce transaction using the electronic wallet. Likewise, the ISP would like to limit the abilities of the application server to ensure that a misbehaving or compromised application server cannot act maliciously toward a user's STB.
Accordingly, there is a need for a way to restrict the features of a user's STB that can be accessed and utilized by an application server within the walled garden. Preferably, the solution to this need will restrict the features at a fine grain, thereby allowing an application server to access only those features which are necessary to provide the service sought by the user.